Biosynthesis of photodynamically active rubellins and structure elucidation of new anthraquinone derivatives produced by Ramularia collo-cygni

Miethbauer, Sebastian; Haase, Susann; Schmidtke, Kai-Uwe; Günther, Wolfgang; Heiser, Ingrid; Liebermann, Bernd

doi:10.1016/j.phytochem.2006.05.003

Cited by 31 publications

(46 citation statements)

References 11 publications

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“…Depletion of the ozone layer has led to an increase in the levels of UVB radiation reaching the Earth's surface (Moseley & Mackie, 1997). Ramularia collo‐cygni produced toxins which induced the formation of reactive oxygen species (ROS) within the host through light‐dependent photodynamic reactions, producing spotting symptoms (Heiser et al ., 2003, 2004; Miethbauer et al ., 2003, 2006). Increased UVB in these cases may have increased the effectiveness of the toxins produced by Ra.…”

Section: Discussionmentioning

confidence: 99%

Associations between fungal and abiotic leaf spotting and the presence of mlo alleles in barley

Makepeace

Oxley²,

Havis³

et al. 2007

Plant Pathology

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The hypothesis that the increased use of the powdery mildew-resistance gene mlo has caused the increase in spotting diseases of barley over the past 20 years was tested in field trials. Near-isogenic lines with alleles of the Mlo gene for susceptibility or resistance to mildew in two parental backgrounds were trialled at four sites in Scotland and two in Ireland that were prone to spotting diseases, over 3 consecutive years. Mildew was controlled by sprays with quinoxyfen. Disease levels were low in the trials, the two most important diseases being scald caused by Rhynchosporium secalis and ramularia leaf spot caused by Ramularia collo-cygni . There were high levels of abiotic spotting. Lines with mutant mlo alleles consistently developed less Rh. secalis and Ra. collo-cygni , but more abiotic spots. This study indicates that the mlo mildew-resistance gene has not alone been responsible for the rise in spotting diseases over the past 20 years. Possible reasons for the rise are discussed, including the interaction of the mlo gene with the environment.

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Section: Discussionmentioning

confidence: 99%

Associations between fungal and abiotic leaf spotting and the presence of mlo alleles in barley

Makepeace

Oxley²,

Havis³

et al. 2007

Plant Pathology

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“…In fact, these workers showed that, in addition to rubellin D, R. collo‐cygni also produces rubellins A, B, C and E (Fig. 5; Miethbauer et al , 2003; Heiser et al , 2004; Miethbauer et al , 2006). In terms of relative ability to induce peroxidation of α‐linolenic acid, rubellin A exhibited greatest activity, whereas rubellin E was ineffective (Miethbauer et al , 2006).…”

Section: Taxonomymentioning

confidence: 98%

“…5; Miethbauer et al , 2003; Heiser et al , 2004; Miethbauer et al , 2006). In terms of relative ability to induce peroxidation of α‐linolenic acid, rubellin A exhibited greatest activity, whereas rubellin E was ineffective (Miethbauer et al , 2006). It seems likely that rubellin B, which is not soluble in planta , is produced first and is then converted to the more polar rubellin D, which possesses greater solubility in planta (Heiser et al , 2004).…”

Section: Taxonomymentioning

confidence: 99%

Ramularia collo-cygni: the biology of an emerging pathogen of barley

Walters

Havis

Oxley

2008

FEMS Microbiology Letters

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Ramularia collo-cygni is now recognized as an important pathogen of barley in Northern Europe and New Zealand. It induces necrotic spotting and premature leaf senescence, leading to loss of green leaf area in crops, and can result in substantial yield losses. The fungus produces a number of anthraquinone toxins called rubellins, which act as host nonspecific toxins with photodynamic activity. These toxins induce lipid peroxidation and are possibly the cause of the chlorosis and necrosis observed in leaves infected with R. collo-cygni. The fact that the fungus can remain latent in barley plants until flowering, coupled with its very slow growth in vitro, makes it difficult to detect in crops. As a result, the epidemiology of this pathogen remains poorly understood. However, the recent development of rapid and reliable PCR methods for specific detection of R. collo-cygni offers the prospect of increased understanding of its epidemiology and improved disease control.

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“…This was strongly dependent on the presence of light. These toxins induce the peroxidation of α‐linolenic acid, a component of cell membranes, in a light‐dependent manner (Heiser et al ., 2003, 2004; Miethbauer et al ., 2003, 2006).…”

Section: Introductionmentioning

confidence: 99%

A method of inoculating barley seedlings with Ramularia collo‐cygni

Makepeace¹,

Havis²,

Burke³

et al. 2008

Plant Pathology

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A method of inoculating seedlings with the fungus Ramularia collo-cygni , the causal agent of ramularia leaf spot (RLS), an increasingly important problem in barley in Europe and elsewhere, is described. Symptoms of RLS similar to those found in the field were reproduced on seedlings and the fungus was re-isolated from them, fulfilling the third and fourth of Koch's postulates. The method was similar to one used for the related fungus, Mycosphaerella graminicola (anamorph Septoria tritici ), a pathogen of wheat. Briefly, plants were sprayed with a suspension of R. collo-cygni mycelium fragments, incubated at 15 ° C, first in darkness for 48 h then in a 16-h-light/8-h-dark cycle. Disease levels reached saturation when plants were sprayed to runoff with a suspension of 480 cm 2 of mycelium, scraped from the entire surface of 7·5Petri dishes (9 cm diameter) and sieved, in 50 mL water. Growth of seedlings in high light intensity (900 μ mol m -2 s -1 , 16-h daylength) before inoculation increased disease symptoms, but reduced disease when applied after inoculation. In contrast to M. graminicola , near-ultraviolet light after inoculation reduced symptom development. It is proposed that for the full development of RLS, plants should be grown in a stressful environment before inoculation. Nine barley lines were assessed for their resistance to RLS as seedlings and a subset were tested in field trials with natural infection by R. collo-cygni . There was cultivar-by-isolate interaction in the amount of RLS symptoms on seedlings. RLS levels on adult plants in field plots were correlated with RLS scores on seedlings formed by one isolate but not the other.

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Biosynthesis of photodynamically active rubellins and structure elucidation of new anthraquinone derivatives produced by Ramularia collo-cygni

Cited by 31 publications

References 11 publications

Associations between fungal and abiotic leaf spotting and the presence of mlo alleles in barley

Associations between fungal and abiotic leaf spotting and the presence of mlo alleles in barley

Ramularia collo-cygni: the biology of an emerging pathogen of barley

A method of inoculating barley seedlings with Ramularia collo‐cygni

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